1. Field of the Invention
The present invention relates to a comment-added video, and relates to a comment information generation device and a comment information generation method that generate comment information including a trajectory to implement a comment display tracking an object in a video as well as a comment display device and a program that display a comment tracking the object.
2. Background Art
Recently developed networks and widespread mobile phones allow a user of them to enjoy easily and usually a communication with the party at a remote place via a network using video contents and still-image contents. For instance, there is a service letting a plurality of users write their preferences and ideas as text on an existing content at a designated timing on the time axis of the contents. Such a communication using contents is expected to increase more in the future with the development of display devices and communication technologies. To implement such a communication, Patent Document 1 describes a technology of generating a video synthesized with a comment added by a user on a video (comment superimposition), and delivering the same over the Internet.
The system described in Patent Document 1 includes a video server and a comment storage/delivery server, and every comment that each user writes via a network is stored on the comment storage/delivery server, and is superimposed on a video for delivery while setting a reproduction time on the video including the comment written thereon as a reference point (hereinafter, such a video is called a “comment-added video”). Every time a video or a comment-added video is delivered and reproduced, a comment that is newly written by a user is associated with a time on the time axis of the video and is managed by the comment storage/delivery server. In their future delivery, these comments are basically delivered based on the time on the time axis of the video regardless whether they are old or new. Each comment is displayed so as to move on the video or at a constant position on the video in a fixed manner irrespective of the object to which the user posted the comment.
Patent Documents 2 and 3 disclose movie equipment to add text information to a video not via the Internet. Patent Documents 2 and 3 especially propose a method of displaying added text information with a balloon and changing the balloon in accordance with the movement of the object in the video, thus making the user's intention to add the text information understood easily.
Patent Document 4 discloses a chat system displaying a balloon. A balloon is displayed so as not to hide a face image of a user that is synthesized at a specified position on a common background or another displayed balloon.
Patent Document 5 discloses a technology to let a user of a mobile phone or a mobile terminal to input text information or illustration information to a video recording device using the mobile phone or the mobile terminal. The mobile phone or the mobile terminal is equipped with a comment tracking menu to make the tracking frame designated by a user track using a motion vector.    [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-148071    [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-244437    [Patent Document 3] WO 2010/116820    [Patent Document 4] Japanese Patent Application Laid-Open No. 2004-128614    [Patent Document 5] Japanese Patent Application Laid-Open No. 2009-81592